Mobile networking requires that a mobile device be able to communicate, even though the point of attachment to the network may change. This would normally cause problems, as most network addresses are associated with a fixed location. For a mobile device, referred to as a mobile node, to be truly mobile it would require a new network address each time it moved to a different location. This renders mobile networking impractical.
However, mobile networking solutions now exist. For example, for mobile networking using the Internet Protocol (IP) standard, there is a Mobile IP standard. This is disclosed in Request for Comments (RFC) published by the Internet Engineering Task Force (IETF), RFC 2002 and RFC 3220. This standard and other IP standards may serve as examples of the types of techniques used to overcome the fixed networking location requirement.
For example, in Mobile IP, a mobile node has a home agent assigned to it from its home network and a home address. As the mobile node roams away from its home network, the mobile node tells the address of its point of attachment to its home agent. The point of attachment address is referred to as the care-of address (CoA). The network at where the mobile node is attached is referred to as a foreign network, and routers at the foreign network that facilitate the packet transmission into and out of the mobile node are referred to as foreign agents. In some instances, a network may deploy foreign agents for use by mobile nodes from other networks, and home agents for use by mobile nodes on the network in the same device. This reduces the number of devices needed for mobile agent deployment.